When will the next Category 5 hurricane form?
Short Answer
The market anticipates the next Category 5 hurricane will form before November 1, 2026, pricing a 94% probability for this Atlantic-specific outcome. This view appears inflated by misinterpretations of market rules that incorrectly account for the confirmed Category 5 Hurricane Polo in the Eastern Pacific, contrasting with expert meteorological forecasts for an exceptionally suppressed Atlantic basin Category 5 season, which the model reflects at 70.7%.
1. Market Behavior & Drivers
The market's decisive move was the formation of Hurricane Polo as a Category 5 storm in the Eastern Pacific. This event drove an 82.0 percentage point price spike on September 24, 2026, as National Hurricane Center (NHC) and other meteorological reports confirmed the storm's intensity. Leading up to this, the market priced in the increasing probability of Polo's intensification. An 18.0 percentage point spike on September 18 reflected early anticipation of the storm reaching Category 5 strength, followed by an 11.0 point increase on September 22 as it developed.
Before Hurricane Polo's formation dominated market activity, prices had fallen. A 9.0 percentage point drop on September 17 was driven by reports of an "unusually quiet" Atlantic hurricane season and a NOAA forecast for suppressed activity. The driver for a separate 11.0 point spike on September 21 cannot be identified from the provided information.
- Probability for Category 5 before November 1, 2026, appears inflated by Hurricane Polo.
- Atlantic basin activity through late September showed an exceptionally suppressed season.
Who Wins and Why
| Outcome | Market | Model | Why |
|---|---|---|---|
| Before Oct 1, 2026 | 10.0% | 4.0% | Expert forecasts and Atlantic basin observations indicate an exceptionally suppressed season for Category 5 hurricanes. |
| Before Nov 1, 2026 | 94.0% | 70.7% | Market is inflated by Hurricane Polo, a confirmed Category 5 Pacific storm irrelevant to this Atlantic-specific market. |
| Before Dec 1, 2026 | 13.0% | 70.7% | Market is inflated by Hurricane Polo, a confirmed Category 5 Pacific storm irrelevant to this Atlantic-specific market. |
Current Context
A Category 5 hurricane already formed in the Eastern Pacific. Eastern Pacific Hurricane Polo reached Category 5 intensity by September 25, 2026. RAMMB listed Polo with 135 kt (approximately 155 mph) maximum sustained winds on September 25 [1]. Prior NHC guidance indicated 145 kt (165 mph) on September 23–24 [2]. Fox Weather explicitly described Polo as a Category 5 storm [3], and a September 24 NHC forecast discussion confirmed it maintained Category 5 strength [4]. The National Hurricane Center defines Category 5 on the Saffir–Simpson scale as maximum sustained winds of at least 157 mph (137 kt) [5][6][7]. NHC records retrieved are not current through September 25, though one result reports Polo as Category 5 on September 24, indicating the question of the next Category 5's formation date is already resolved [8].
Pacific basin conditions support high-intensity storms, contrasting the Atlantic. The Eastern Pacific's July–September period, its peak season, offers a more favorable environment for extreme-intensity storms [9]. NOAA's May 21, 2026, Eastern Pacific outlook favored an above-normal season with a 70% probability, projecting 15–22 named storms, 9–14 hurricanes, and 5–9 major hurricanes [9]. NHC season summaries updated through September 2–3, 2026, documented two major hurricanes in the Eastern Pacific (Genevieve at 140 kt and Karina at 125 kt), with Lowell also listed as a major hurricane at 140 kt [10]. Conversely, the Atlantic basin had no confirmed Category 5 storm by September 25 [5] and had produced zero hurricanes and zero major hurricanes by September 2–3 [11]. Current Atlantic activity includes Tropical Storms Fay and Gonzalo, with Gonzalo expected to weaken and Fay facing a hostile environment [5][12][13]. Colorado State University's 2026 Atlantic seasonal forecast anticipated a well-below-normal season: 9 named storms, 4 hurricanes, and 1 major hurricane, attributing this to strengthening El Niño and increased Atlantic vertical wind shear [14]. NOAA's August 2026 Atlantic outlook assigned a 75% probability to a below-normal season, projecting 0–2 major hurricanes, consistent with historical strong El Niño seasons [15][16][17].
Prediction markets reflect low Atlantic Category 5 probabilities. A Kalshi-tracked market, reported by PredictMarketCap on September 20, 2026, priced the probability of an Atlantic Category 5 forming before October 1 at 7%, before November 1 at 3%, and before December 1 at 15% [18]. This market resolves on December 1 [18]. Prediction markets offer deadline-based contracts where odds reflect trader-implied probabilities, not precise meteorological forecasts [19][18]. Separately, a Polymarket contract estimated a 97% probability against a Category 5 hurricane making landfall in the contiguous United States before 2027; this addresses landfall, not formation anywhere in a basin [20]. No retrieved sources provided verifiable 2026 prediction market data for the next Category 5 hurricane's formation date beyond these specific Atlantic contracts [21].
Sources (21)
- 1RAMMB: TC Real-Time: EP172026 - Major Hurricane POLOrammb-data.cira.colostate.edu
- 2Hurricane Polo Forecast Discussionprod-east-nhc.woc.noaa.gov
- 3Bryan Norcross: Fall nor'easter, Nolo eyes Hawaii, Polo targets Mexico | Fox Weatherfoxweather.com
- 4Hurricane Polo Forecast Discussionnhc.noaa.gov
- 5National Hurricane Center - NOAAnhc.noaa.gov
- 62026 Atlantic Hurricane Seasonnhc.noaa.gov
- 7NOAA hurricane season datesnhc.noaa.gov
- 82026 Atlantic Hurricane Season (text)nhc.noaa.gov
- 9Climate Prediction Center - Expert Assessments: East Pacific Hurricane Outlookcpc.ncep.noaa.gov
- 102026 Eastern Pacific Hurricane Seasonnhc.noaa.gov
- 112026 Atlantic Hurricane Seasonnhc.noaa.gov
- 12Tropical Storms Fay, Gonzalo hurricane tracker. Is Florida at risk?naplesnews.com
- 13Hurricane season maps tracker: forecasts and moreweather.com
- 14CSU Hurricane Seasonal Forecastingtropical.colostate.edu
- 15Climate Prediction Center - Atlantic Hurricane Outlookcpc.ncep.noaa.gov
- 16Climate Prediction Center - Atlantic Hurricane Outlookcpc.ncep.noaa.gov
- 17Climate Prediction Center - Atlantic Hurricane Outlookcpc.ncep.noaa.gov
- 18When will next Category 5 hurricane form in 2026 Odds | Kalshipredictmarketcap.com
- 19When will the next Category 5 hurricane form? | Prediction Marketscoinbase.com
- 20Will any Category 5 hurricane make landfall in the US in before 2027?polymarket.com
- 21https://www.nhc.noaa.gov/archive/2025/ep14/ep142025.fstadv.025.shtmlnhc.noaa.gov
2. Price Chart
Historical Price (Probability)
Outcome probability
Date
3. Significant Price Movements
Notable price changes detected in the chart, along with research into what caused each movement.
📈 September 24, 2026: 82.0pp spike
Price increased from 12.0% to 94.0%
Outcome: Before Nov 1, 2026
What happened: The primary driver of the 82.0 percentage point price spike was the confirmed formation of Hurricane Polo as a Category 5 storm in the Eastern North Pacific on or around September 24, 2026 [1]. Official reports from the National Hurricane Center (NHC) on September 24 and 25, 2026, indicated Polo was a powerful Category 5 hurricane, directly fulfilling the market's outcome "Before Nov 1, 2026" [1]. This event occurred despite a predicted below-normal Atlantic hurricane season with low chances of a late-season Category 5 event [2]. Based on the provided information, social media activity was irrelevant to this price movement.
📈 September 22, 2026: 11.0pp spike
Price increased from 1.0% to 12.0%
Outcome: Before Nov 1, 2026
What happened: The primary driver of the 11.0 percentage point spike on September 22, 2026, for a Category 5 hurricane forming before November 1, 2026, was the development of Hurricane Polo. By September 24, 2026, Hurricane Polo was already confirmed as a Category 5 hurricane in the eastern North Pacific [3]. This rapid intensification, or the widespread reporting of its imminent Category 5 status around September 22, directly influenced expectations for the market's "Before Nov 1, 2026" outcome. No specific social media activity from key figures or viral narratives were identified in the provided research, making its role as a primary driver unascertainable.
📈 September 21, 2026: 11.0pp spike
Price increased from 3.0% to 14.0%
Outcome: Before Nov 1, 2026
What happened: The primary driver for the 11.0 percentage point price spike on September 21, 2026, cannot be definitively identified from the provided research. No social media activity or specific traditional news announcements directly preceding or coinciding with the September 21 spike are mentioned that would explain an increase [1-12]. While Eastern Pacific Hurricane Polo was reported to have reached Category 5 intensity by September 25, the research does not provide timing details to confirm if forecasts or its actual formation on or before September 21 caused the market movement, assuming the market refers to any global basin [4][2]. Therefore, social media was irrelevant based on the available information.
📈 September 18, 2026: 18.0pp spike
Price increased from 2.0% to 20.0%
Outcome: Before Nov 1, 2026
What happened: The 18.0 percentage point spike on September 18, 2026, for the "Before Nov 1, 2026" outcome was primarily driven by increasing market anticipation of Eastern Pacific Hurricane Polo reaching Category 5 intensity. Although Polo officially reached Category 5 on September 22–23 [4][2][5][6], the market likely reacted to escalating forecasts or high probabilities for its strengthening in the preceding days. The provided web research does not contain specific social media posts, influential accounts, or traditional news reports from September 18 detailing such forecasts [1-18]. Therefore, social media activity cannot be identified as the primary driver based on the available information.
📉 September 17, 2026: 9.0pp drop
Price decreased from 11.0% to 2.0%
Outcome: Before Nov 1, 2026
What happened: The primary driver of the prediction market price drop was the prevailing meteorological outlook indicating a suppressed hurricane season. On September 17, 2026, the Atlantic basin was experiencing an "unusually quiet" season with no hurricanes through at least September 11, and NOAA's August update maintained a forecast for a "below-normal" Atlantic season [4][7][8][9][10]. These traditional news reports and forecasts, suggesting a reduced likelihood of a major hurricane, likely led market participants to decrease confidence in a Category 5 forming before November 1, 2026 [11][12]. There is no evidence of social media activity serving as a primary driver, contributing accelerant, or having any significant impact on the price movement for this date.
Sources (12)
- 1Eastern North Pacific Tropical Weather Discussionnhc.noaa.gov
- 2Talking the Tropics With Mike: Last day of the Atlantic hurricane season! - Action News Jaxactionnewsjax.com
- 3Hurricane Polo Forecast Discussionnhc.noaa.gov
- 4Hurricane season maps tracker: forecasts and moreweather.com
- 5Tracking Nolo and Polo in the Pacific: Hawaii faces its biggest hurricane threat of the season this weekendtheweather.com
- 6Hurricane Odalys Strengthens Over Open Eastern Pacific, Weakening Trend Expected This Weekendsea.weathernews.com
- 7Talking the Tropics With Mike: Last day of the Atlantic hurricane season! - 104.5 WOKVwokv.com
- 8NOAA maintains prediction for below-normal Atlantic...noaa.gov
- 9CSU Hurricane Seasonal Forecastingtropical.colostate.edu
- 102026 Atlantic Hurricane Seasonnhc.noaa.gov
- 11Fall 2026 Climate Outlook for northeastern South Carolina and southeastern North Carolinaweather.gov
- 12Topicsweather.gov
4. Market Data
Contract Snapshot
This Kalshi prediction market resolves based on when the next Category 5 hurricane forms. A "YES" outcome occurs if a Category 5 hurricane forms before the contract's specified deadline, such as October 1, 2026, November 1, 2026, or December 1, 2026. A "NO" outcome occurs if a Category 5 hurricane does not form by the respective deadline. The maximum payout date for the "Before Oct 1, 2026" contract is September 30, 2026, and no special settlement conditions are detailed.
Available Contracts
Market options and current pricing
| Outcome bucket | Yes (price) | No (price) | Last trade probability |
|---|---|---|---|
| Before Oct 1, 2026 | $0.09 | $1.00 | 10% |
| Before Nov 1, 2026 | $0.21 | $0.89 | 94% |
| Before Dec 1, 2026 | $0.13 | $0.95 | 13% |
Market Discussion
A precise date for the next Category 5 hurricane cannot be responsibly forecast by official sources, as seasonal outlooks provide basin-level probabilities, and intensity forecasts are generally limited to roughly five days [1][2][3][4]. While Hurricane Polo was classified as a Category 5 on September 22, 2026 [5][6][7], and Hurricane Lowell reached Category 5 intensity on September 2, 2026 [4][8], public and trader commentary after these events focused on immediate landfall risks or the below-normal Atlantic season rather than predicting another Category 5 [9][10][11].
Sources (11)
- 12026 Atlantic Hurricane Seasonnhc.noaa.gov
- 2Climate Prediction Center - Atlantic Hurricane Outlookcpc.ncep.noaa.gov
- 3Climate Prediction Center - Expert Assessments: East Pacific Hurricane Outlookcpc.ncep.noaa.gov
- 4https://www.nhc.noaa.gov/archive/2026/ep12/ep122026.discus.026.shtmlnhc.noaa.gov
- 5Hurricane Polo Public Advisoryprod-east-nhc.woc.noaa.gov
- 6https://prod-east-nhc.woc.noaa.gov/archive/2026/ep17/ep172026.public.008.shtmlprod-east-nhc.woc.noaa.gov
- 7https://prod-east-nhc.woc.noaa.gov/archive/2026/ep17/ep172026.public.010.shtmlprod-east-nhc.woc.noaa.gov
- 8https://www.nhc.noaa.gov/archive/2026/ep12/ep122026.discus.038.shtmlnhc.noaa.gov
- 9Hurricane Polo threatens Mexico and future Tropical Storm Nolo threatens Hawaiiinteractivebrokers.com
- 102026 Atlantic hurricane seasonal outlook August update...facebook.com
- 11NOAA maintains prediction for below-normal Atlantic...noaa.gov
5. Trust Index
Order book is critically thin.
Primary risk· Trade quality
How it adds up
Integrity80% of score87Strong
Trade quality20% of score6Avoid
Includes the cost to trade: a $10,000 order can't be filled here because the order book is too thin.
Trust score71Good
Weighted blend with hard caps — a critically weak safety pillar, or a severe trading anomaly, caps the total regardless of the rest. Full methodology · About the Trust Index
Trust profile
Integrity4 screens run · 6 don't apply
6. What official data from the National Hurricane Center and RAMMB confirms Hurricane Polo reached Category 5 intensity in September 2026?
| Maximum Sustained Winds (NHC) | 165-180 mph (Category 5) [1][2][3][4] |
|---|---|
| Category 5 Wind Threshold | 157 mph [1][2][3][4] |
| RAMMB Reported Intensity | 135 kt (approx. 155 mph) [5][6] |
The National Hurricane Center officially confirmed Hurricane Polo reached Category 5 intensity. Official public advisories explicitly classified Hurricane Polo as a Category 5 storm in September 2026, reporting maximum sustained winds between 165 mph and 180 mph, exceeding the 157 mph threshold for this category [1][2][3][4]. NHC data from September 22, 2026, indicated approximately 165 mph maximum sustained winds and a 920 mb minimum central pressure [1][2][3][7][8][9][10][11]. Additionally, a NOAA satellite summary indicated Polo reached 180 mph [1][2][3][7][8][9][10][11].
RAMMB data indicated major hurricane strength but lacked explicit Category 5 confirmation. While the NHC provided explicit classification, available research does not independently establish RAMMB’s confirmation for Polo reaching Category 5 intensity [7][8][9][10][11]. RAMMB’s official real-time tropical cyclone page identified EP172026 as “Major Hurricane POLO,” with its guidance record listing a 135 kt intensity, equivalent to about 155 mph, at 06 UTC on September 25 [5][6]. This intensity is consistent with a major hurricane and near or within Category 5 operational intensity; however, the retrieved web results lack a RAMMB-hosted page or analysis specifically confirming Polo reached Category 5 [7][8][9][10][11]. Therefore, the evidence currently supports the Category 5 claim through NHC only [7][8][9][10][11].
Sources (11)
- 1Hurricane Polo Public Advisorynhc.noaa.gov
- 2Hurricane Polo at 17.1°N - 105.5°W - NOAA / NESDIS / STARgoes.noaa.gov
- 3NOAA Satellites Monitor Hurricane Polo's Rapid...nesdis.noaa.gov
- 4Polo strengthens to a Category 5 hurricane off Mexico's...wthitv.com
- 5RAMMB: TC Real-Time: EP172026 - Major Hurricane POLOrammb-data.cira.colostate.edu
- 6https://rammb-data.cira.colostate.edu/tc_realtime/products/storms/2026ep17/ripastbl/2026ep17_ripastbl_202609250600.txtrammb-data.cira.colostate.edu
- 7Hurricane Polo Forecast Discussion (text)nhc.noaa.gov
- 8Hurricane POLO (text)nhc.noaa.gov
- 9Hurricane POLO (text)nhc.noaa.gov
- 10Hurricane Polo Public Advisorynhc.noaa.gov
- 11Hurricane Polo Public Advisorynhc.noaa.gov
7. What specific atmospheric and oceanic conditions in the Eastern Pacific basin led to Hurricane Polo's rapid intensification between September 22 and September 24, 2026?
| Intensification Period | September 22-24, 2026 [1][2] |
|---|---|
| SST Anomaly (Niño 1+2) | 4.1°C in August [3] |
| Strength Increase | Tropical storm to Category 5 [1][4][5] |
Hurricane Polo underwent rapid intensification from September 22 to September 24, 2026, driven by nearly ideal environmental conditions. During this period, the storm intensified from tropical-storm to Category 5 strength [1][4][5]. These optimal conditions included weak vertical wind shear, abundant atmospheric moisture, unusually warm ocean water, and strong upper-level outflow [1][2][6][7][8]. This combination provided both the thermodynamic and dynamical support necessary for deep convection to organize and rapidly lower the storm's central pressure [1][4][5].
Exceptional oceanic heat content provided crucial fuel for Polo's rapid intensification. The Eastern Pacific waters near the Mexican coast were unusually warm, largely untouched by prior storms, which allowed Hurricane Polo to extract significant ocean heat fluxes [2][4]. A NOAA ocean briefing from September 2026 confirmed these unusually warm Eastern Tropical Pacific conditions, noting a strong coastal Niño with a Niño 1+2 sea-surface-temperature anomaly of 4.1°C in August, alongside active marine heatwaves that favored high oceanic heat availability [3].
Favorable atmospheric conditions further contributed to Polo's rapid strengthening. These included continued weak vertical wind shear, abundant atmospheric moisture, and strong upper-level outflow [1][2]. A mid-level ridge situated over Texas helped to steer the storm over these highly favorable waters [2]. Additionally, Polo's small, compact circulation facilitated efficient spin-up and organization [2][9]. While the conditions were broadly favorable, specific numerical values for vertical wind shear, upper-level outflow, midlevel humidity, sea-surface temperature, or ocean heat content for Polo during this period were not exposed in the retrieved evidence or NOAA archives [6][7][8][10][11].
Sources (11)
- 1Explosive Intensification for Hurricane Poloscience.nasa.gov
- 2Hurricane Polo intensified to a Category 5 in less than a daywashingtonpost.com
- 3Global Ocean Monitoring: Recent Evolution, Current Status, andcpc.ncep.noaa.gov
- 4Hurricane Polo weakens some after feasting on hot El Niño...cnn.com
- 5NOAA Satellites Monitor Hurricane Polo's Rapid...nesdis.noaa.gov
- 6Hurricane POLO (text)nhc.noaa.gov
- 7Tropical Storm Polo Forecast Discussion (text)nhc.noaa.gov
- 8Hurricane POLO - National Hurricane Center - NOAAnhc.noaa.gov
- 9Hurricane Polo Forecast Discussionnhc.noaa.gov
- 10Index of /pub/data/nccf/com/wfs/prod/wrs.20260923/00nomads.ncep.noaa.gov
- 11Index of /pub/data/nccf/com/glmp/prod/glmp.20260923nomads.ncep.noaa.gov
8. How did 2026 hurricane season conditions in the Atlantic basin compare to the Eastern Pacific, based on CSU's seasonal forecast and observed activity through September?
| Atlantic ACE (early Sept) | 4.4 (approximately 89–90% below normal ACE) [1][2] |
|---|---|
| Atlantic Hurricanes (Sept 22) | Zero [3][4][2] |
| Eastern Pacific ACE (Sept 3) | 84.4 (25% above normal) [3][5][6] |
The 2026 hurricane season demonstrated a significant El Niño-driven basin contrast. Through September, observed activity in the Atlantic basin was dramatically suppressed, while the Eastern Pacific experienced enhanced activity, strongly validating the directional forecast [7][3][5]. This notable suppression in the Atlantic was primarily attributed to moderate or strong El Niño conditions and the resulting high Atlantic vertical wind shear [7][8].
Atlantic hurricane activity remained exceptionally quiet through September. By July 28, only Tropical Storms Arthur and Bertha had formed, with zero hurricanes or major hurricanes, contributing to an Accumulated Cyclone Energy (ACE) of 2.6, which was 71% below the 1991–2020 normal for that date [9]. As of early September, the Atlantic had produced only 5 named storms, zero hurricanes, and an ACE of 4.4, approximately 89–90% below normal [1][2]. Through September 22, the Atlantic continued to report zero hurricanes, marking a satellite-era record start [3][4][2]. NOAA's updated Atlantic outlook assigned a 75% probability to below-normal activity, forecasting 7–13 named storms, 2–6 hurricanes, and up to 2 major hurricanes for the full season [10][11][12].
Eastern Pacific activity significantly surpassed the Atlantic, aligning with expectations. The Eastern Pacific basin was materially more active than the Atlantic, consistent with NOAA's expectation for an above-normal season [3]. By September 3, the National Hurricane Center (NHC) reported 13 named storms, 4 hurricanes, 2 major hurricanes, and an ACE of 84.4, which was 25% above normal [3][5][6]. By this date, the Pacific had already surpassed Colorado State University's entire Atlantic forecast for named storms and matched or exceeded its forecast hurricane and major hurricane counts [3][5][6]. The Eastern and Central Pacific also produced high-end storms before September, with Genevieve and Lowell reaching 140 knots, a strength equivalent to a Category 5 hurricane [5][6][13][10][2].
Sources (13)
- 12026 Atlantic Hurricane Seasonnhc.noaa.gov
- 2Topicsweather.gov
- 3NOAA maintains prediction for below-normal Atlantic...noaa.gov
- 4The 2026 Atlantic hurricane season is experiencing...instagram.com
- 52026 Eastern Pacific Hurricane Seasonnhc.noaa.gov
- 62026 Eastern Pacific Hurricane Seasonnhc.noaa.gov
- 7CSU Hurricane Seasonal Forecastingtropical.colostate.edu
- 8FORECAST OF ATLANTIC HURRICANE ACTIVITY FOR 2026tropical.colostate.edu
- 92026 Atlantic Hurricane Seasonnhc.noaa.gov
- 10Climate Prediction Center - Expert Assessments: East Pacific Hurricane Outlookcpc.ncep.noaa.gov
- 11Climate Prediction Center - Atlantic Hurricane Outlookcpc.ncep.noaa.gov
- 12Climate Prediction Center - Atlantic Hurricane Outlookcpc.ncep.noaa.gov
- 132026 Central Pacific Hurricane Seasonnhc.noaa.gov
9. Which specific advisories from the National Hurricane Center are considered authoritative for resolving hurricane intensity markets for the 2026 season?
| Category 5 Wind Speed | 137 kt (157 mph) [1][2][3][4] |
|---|---|
| Operational Advisory Frequency | Every six hours [3][4] |
| Definitive Settlement Source | Tropical Cyclone Report (TCR) post-analysis best track [5][6] |
The NHC provides distinct authoritative sources for hurricane intensity market resolution. For resolving hurricane intensity markets for the 2026 season, the National Hurricane Center (NHC) identifies both operational advisories and post-storm analyses as authoritative, depending on the market's timing and rules [5][6]. The relevant intensity metric for settlement is the maximum sustained surface wind. For real-time operational resolution, the Tropical Cyclone Public Advisory (TCP) and Tropical Cyclone Forecast/Advisory (TCM) are considered authoritative [5][1][3]. NHC's official operational intensity information, which also includes the Tropical Cyclone Discussion (TCD), is published every six hours at 0300, 0900, 1500, and 2100 UTC [3][4]. These operational products should be used together if a market resolves before the definitive Tropical Cyclone Report (TCR) is released [5][6][1].
The Tropical Cyclone Report provides definitive post-storm intensity resolution. For definitive settlement, particularly regarding whether a 2026 hurricane reached Category 5 intensity, the storm's official Tropical Cyclone Report (TCR), specifically its post-analysis best track, is the authoritative NHC source [5][6]. The best track is a comprehensive post-storm analysis containing six-hourly analyzed maximum sustained winds [5][6]. While the TCM and TCD serve as authoritative real-time advisories, the post-season best track is considered the stronger final settlement record, as operational advisories can be revised [3][4][7][8]. A Category 5 hurricane is defined by a maximum sustained surface wind of at least 137 kt (157 mph) [1][2][3][4]. Unless specific market rules defer to post-season reanalysis, operational resolution typically utilizes the first dated regular NHC advisory reporting maximum sustained winds of at least 137 kt (157 mph) [1][3]. For any settlement, it is crucial to use NHC-analyzed maximum sustained wind, and not model output, gusts, pressure, or a forecast [3][4].
Sources (8)
- 1Glossary of NHC Terms - National Hurricane Centernhc.noaa.gov
- 2NHC Glossaryweather.gov
- 32. Forecast verification procedures - National Hurricane Centernhc.noaa.gov
- 4National Hurricane Center Forecast Verification (text)nhc.noaa.gov
- 5NHC Tropical Cyclone Text Product Descriptionsnhc.noaa.gov
- 6NHC Text Product Descriptions - National Hurricane Centernhc.noaa.gov
- 7Hurricane POLOnhc.noaa.gov
- 8Hurricane Polo Forecast Discussion (text)nhc.noaa.gov
10. How accurately did Colorado State University's 2026 pre-season Atlantic forecast predict observed hurricane activity as of late September 2026?
| CSU August Forecast (Named Storms) | 9 named storms [1][2][3][4] |
|---|---|
| Observed Named Storms (late Sep 2026) | 6 named storms [1][2][3][4] |
| Observed Major Hurricanes (late Sep 2026) | 0 major hurricanes [1][2][3][4] |
Colorado State University's (CSU) Atlantic hurricane forecast for 2026 showed strong qualitative accuracy. The forecast correctly anticipated a strongly suppressed season as of late September [1][2][5][3][4]. While the full season extends through November 30, the quantitative accuracy remains provisional and mixed [1][2][5][6]. The National Oceanic and Atmospheric Administration (NOAA) corroborated this outlook, also characterizing the 2026 season as below normal in its contemporaneous assessment [6][7].
Observed activity diverged quantitatively from CSU's specific forecast metrics. By late September, observed activity included 6 named storms, 0 hurricanes, and 0 major hurricanes, contrasting with CSU's August forecast predicting 9 named storms, 4 hurricanes, and 1 major hurricane for the entire season [1][2][3][4]. This indicates that the forecast underpredicted the eventual named-storm count to date by three, while overpredicting the hurricane and major-hurricane activity observed so far [3][4].
No Category 5 hurricane was reported by late September 2026. The available information as of late September 2026 did not list the formation of a Category 5 hurricane, and the prediction-market event asking "When will the next Category 5 hurricane form?" remained unresolved as of September 25 [3][4][8]. Although CSU forecast one major hurricane, Category 5 is a subset of major hurricanes, and the available CSU sources do not offer a separate Category 5 probability or formation-date forecast [3].
Sources (8)
- 1CSU Hurricane Seasonal Forecastingtropical.colostate.edu
- 2FORECAST OF ATLANTIC HURRICANE ACTIVITY FOR 2026tropical.colostate.edu
- 3A Historic Atlantic Hurricane Season,...weather.gov
- 42026 Atlantic Hurricane Seasonnhc.noaa.gov
- 52026 Atlantic Hurricane Season (text)nhc.noaa.gov
- 6Climate Prediction Center - Atlantic Hurricane Outlookcpc.ncep.noaa.gov
- 7Climate Prediction Center - Atlantic Hurricane Outlookcpc.ncep.noaa.gov
- 8Tropical Cyclone Names - National Hurricane Center - NOAAnhc.noaa.gov
11. What Could Change the Odds
Key Catalysts
The Eastern Pacific Hurricane Polo reached Category 5 intensity on September 22–23, 2026, establishing the next Category 5 in the 2026 season chronology [1][2]. As of September 25, 2026, the Atlantic basin has shown an exceptionally suppressed season, with no Atlantic hurricanes by late September [3][4]. NOAA's 2026 Atlantic outlook favored a below-normal season with a 55% probability [5][6]. The August 6 Atlantic outlook assigned a 75% chance to a below-normal season, forecasting only 0–2 major hurricanes [7][3]. CSU's August forecast expected 4 Atlantic hurricanes and 1 major hurricane for the full season, including Category 3–5 storms; this forecast did not specify a date or predict a Category 5 [3][4][8][9][10]. The immediate late-September Atlantic setup is bearish for near-term Category 5 formation, as Tropical Storm Fay was expected to dissipate and an African tropical wave had only a chance of development [2][11].
Prediction-market catalysts for a remaining 2026 Atlantic Category 5 include a rapidly organizing storm over unusually warm water, falling wind shear, favorable upper-level outflow, and a credible track into the Gulf/Caribbean [12][13][14]. Bearish catalysts are continued strong El Niño-related shear, dry air, hostile model guidance, and passage of the late-September/October windows without intensification [12][13][14]. The highest-probability window, should the market settle on an Atlantic Category 5, is the remaining peak-season interval through October 31; November 1–30 is a lower-probability tail [7][3]. The market should reprice sharply on NHC evidence of a named storm, rapid intensification, very low shear, high ocean heat content, and a forecast peak near or above 137 kt [7][3][15]. Bullish signals include an NHC disturbance with increasing formation probability, persistent organized convection, an improving inner core, low vertical wind shear, warm/high-ocean-heat-content waters, and model consensus for rapid intensification [16][7][15]. Bearish signals include NHC 'no formation expected' language, dry air, increasing shear, cooler water, land interaction, or forecasts peaking below 137 kt [16][7][15]. The NHC's operational outlook, providing 2-day and 7-day tropical-cyclone formation probabilities, is the key near-term catalyst [16][15].
Key Dates & Catalysts
- Expiration: September 08, 2026
- Closes: December 01, 2026
Sources (16)
- 1Talking the Tropics With Mike: Last day of the Atlantic hurricane season! - 104.5 WOKVwokv.com
- 2Hurricane season maps tracker: forecasts and moreweather.com
- 32026 Atlantic Hurricane Seasonnhc.noaa.gov
- 42026 Atlantic hurricane seasonen.wikipedia.org
- 5Climate Prediction Center - Atlantic Hurricane Outlookcpc.ncep.noaa.gov
- 6Climate Prediction Center - Atlantic Hurricane Outlookcpc.ncep.noaa.gov
- 7Climate Prediction Center - Atlantic Hurricane Outlookcpc.ncep.noaa.gov
- 8FORECAST OF ATLANTIC HURRICANE ACTIVITY FOR 2026tropical.colostate.edu
- 9August 2026 update to CSU’s seasonal Atlantic hurricane forecast continues prediction for well below-average season By MarComm. Staff How does CSU put its seasonal hurricane forecast together? Hurricane landfalling probability included in 2026 reporttropical.colostate.edu
- 10CSU Hurricane Seasonal Forecastingtropical.colostate.edu
- 11https://rammb-data.cira.colostate.edu/tc_realtime/products/storms/2026ep17/ripastbl/2026ep17_ripastbl_202609250600.txtrammb-data.cira.colostate.edu
- 12Category 5 US Landfall Before 2027: Market at 13%lines.com
- 13When will the next Category 5 hurricane form — 11% · Kalshi | SimpleFunctionssimplefunctions.dev
- 14Will any Category 5 hurricane make… 5.9% Odds | Polymarketpredictmarketcap.com
- 15https://www.nhc.noaa.gov/text/refresh/MIATWOAT+shtml/061706_MIATWOAT.shtmlnhc.noaa.gov
- 16Graphical Tropical Weather Outlook - National Hurricane Centernhc.noaa.gov
13. Historical Resolutions
Historical Resolutions: 1 markets in this series
Outcomes: 0 resolved YES, 1 resolved NO
Recent resolutions:
- KXNEXTCAT5HURDATE-26DEC01-26SEP01: NO (Sep 01, 2026)
